It is worth noting that the metallicity does not always increase with decreasing radius. In fact, for a number of systems, the Fe abundance was found to peak a few kpc outside of the core while decreasing towards its very centre. Although historically discovered and investigated in the Centaurus cluster [1]}, these drops are more commonly found in lower-mass systems [2]}, [3]}, [4]}, [5]}, [6]}. Whether the presence of these drops is truly related to mass of the system (and/or the strength of their cool core) is not clear yet. Indeed, abundance drop detections might be affected by selection biases – originating from either the usually larger distance of clusters (resulting in a poorer spatial resolution, hence no detected drop), or the selection itself of the currently most studied systems.
